/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.ls.fw.mvc.springmvc.support.accept;

import java.util.Collections;
import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.http.MediaType;
import org.springframework.util.MimeTypeUtils;
import org.springframework.web.accept.ContentNegotiationStrategy;
import org.springframework.web.context.request.NativeWebRequest;

/**
 * A ContentNegotiationStrategy that returns a fixed content type.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class ContentTypeNegotiationStrategy implements ContentNegotiationStrategy {

	private static final Log logger = LogFactory.getLog(ContentTypeNegotiationStrategy.class);

	@Override
	public List<MediaType> resolveMediaTypes(NativeWebRequest webRequest) {
		Object responseobj  = webRequest.getNativeResponse();
		if(responseobj!=null){
			if(responseobj instanceof HttpServletResponse){
				HttpServletResponse response = (HttpServletResponse)responseobj;
				String contentType = response.getContentType();
				if(StringUtils.isNotBlank(contentType)){
					MediaType mediaType = MediaType.parseMediaType(contentType);
					if(logger.isDebugEnabled()){
						logger.debug("response media types is " + mediaType + " !");
					}
					return Collections.singletonList(mediaType);
				}
			}
		}
		Object obj  = webRequest.getNativeRequest();
		if(obj!=null){
			if(obj instanceof HttpServletRequest){
				HttpServletRequest request = (HttpServletRequest)obj;
				String contentType = request.getContentType();
				if(StringUtils.isNotBlank(contentType)){
					MediaType mediaType = MediaType.parseMediaType(contentType);
					if(logger.isDebugEnabled()){
						logger.debug("request media types is " + mediaType + " !");
					}
					return Collections.singletonList(mediaType);
				}
			}
		}
		
		return Collections.emptyList();
	}

}
